1. Field of the Invention
This invention relates generally to wireless telecommunication networks wherein multiple wireless systems or service providers are capable of servicing a particular mobile terminal or mobile station, and pertains more specifically to methods and apparatus for the mobile station to select a particular wireless service provider from which service is to be obtained.
2. Prior Art
The specification of system selection protocols has been an ongoing effort for a number of years in the wireless telecommunications field, in particular in the cellular telephone area. For example, in the AMPS system the mobile station is given a choice between possible serving systems based on the system identification (SID) parameter, wherein in one technique the mobile station is enabled to identify and select its Home system when it is encountered. Another technique involves setting a certain frequency band preference to control the band scanning process. For example, possible band preferences may be: scan only the A band, scan only the B band, scan only the band containing the Home SID (A or B), or a standard technique, where the Home band is scanned first, followed by the other band.
Another development is referred to as Intelligent Roaming, which is an expansion of the positive/negative SID list technique. In the Intelligent Roaming approach various mechanisms are provided to: use a broadcast System Operator Code (SOC) as well as the SID to prioritize systems; provide for three different priorities (in addition to Home and Unidentified); for prioritizing the 800 MHz and 1900 MHz bands for scanning; for transitioning to a more preferred system when camped on a less preferred system; and for controlling the display of system identification text (using the so-called alpha-tags). When using the broadcast SOC and the SID the mobile station maintains one list for each, and configurable arbitration is used to control selection when the SID and SOC have different priorities.
One benefit of using the SOC is a reduction in database size, as the SOC(s) for a particular operator do not change between different areas (like the SID). As such, one SOC entry in the mobile station database can encompass all systems belonging to a specific operator, which could require a prohibitive number of SID entries to achieve the same result. When combined with the area-specific system designation of the SID, this technique provides a means to assign a general priority for a particular operator (based on the SOC), while also providing area-specific exceptions (based on the SID).
Intelligent Roaming provides five different system classes or priorities that, in descending priority order are: Home (SID or SOC); Partner; Favored; Neutral (designated by a failure to match SID parameters in the mobile station's database; and Forbidden (utilized only to make emergency calls). The Partner priority provides a method to set multiple SID and SOC entries in the database with an equivalent priority with the HOME SID and SOC.
The Favored priority provides a method for having two preferred systems in the same area with one, the Favored system, serving as a less desirable backup for the other (the Home or Partner system).
In the current North American cellular system, any given market area may be serviced by up to two competing service providers of cellular air time communication services (wireless carriers). By Federal Communications Commission (FCC) regulations, the two competing wireless carriers are assigned different groups of frequencies through which services are provided. A frequency set typically includes control channels and voice channels. The control channels are used for preliminary communications between a mobile station and a cell site for setting up a call, after which a voice channel is assigned for the mobile station's use on that call. The assigned frequency sets are generally referred to as “A band frequencies” and “B band frequencies”. Typically, the A band frequencies are reserved for non-wireline service providers, while the B band frequencies are reserved for the incumbent wireline service providers. While each frequency set for a given cellular service market area is assigned to only one service provider, in different market areas the same frequency set may be assigned to different service providers or companies.
Depending upon which wireless carrier the user of the mobile station subscribes to, the home frequency set of the user may correspond to the A frequency band or the B frequency band. Whenever the mobile station places a call, the unit will ordinarily attempt to use the home frequency set to establish the call. If a call is handled outside of the user's home market area, then the unit is said to be “roaming” and service will be attempted through a frequency set of a non-home service provider. Typically, the user's home service provider will have a roaming agreement or reciprocal billing arrangement with the non-home service provider to permit service to be extended to the user's mobile unit when it is roaming in the non-home service provider's market area.
The serving areas of mobile service in based on the system identification (SID) parameter. The mobile station is enabled to identify and select its home system when it is encountered.
A development in the wireless industry provided positive/negative SID lists, where the positive SID list contains SID information for desirable non-home systems, while the negative SID list contains SID information for those systems that are to be used only in the event an emergency call needs to be originated by the mobile station. This technique may be used in conjunction with Home SID/band preferences discussed above to provide a desired scanning order with restrictions. An example of a mobile station that utilizes negative SIDs is disclosed by Blair, U.S. Pat. No. 4,916,728. As an alternative to negative SIDs, some mobile stations are programmed with positive or preferred SIDs. Positive or preferred SIDs are SIDs on which the mobile station should attempt to obtain service when selecting a cellular carrier frequency. An example of a mobile station that utilizes preferred SIDs is disclosed by Barber et al., U.S. Pat. No. 5,442,806. The uses of preferred SIDs facilitate the selection of a preferred service provider when the mobile station is roaming.
Another development in the wireless industry is to offer prepaid wireless services. An example of a provider of prepaid wireless service is TracFone™ Wireless, Inc., which functions as a reseller of airtime from various carriers in the United States.
Such resellers may obtain their customers by selling mobile stations to retailers who in turn sell the mobile stations to the end user. Once the end user buys the mobile station, the end user contacts the reseller's customer service for activation of the handset. Contact can be made with a phone call or through a website. The customer is then asked to provide the Phone Serial Number (ESN) and the postal ZIP Code of the area where the customer will be using the mobile station most often. The determination of the carrier to be utilized for that specific end user is controlled by resell agreements with the carriers in the customer's indicated location of use, as determined by the ZIP code. Based on the wireless carrier that is selected for the entered ZIP code, a home SID is loaded into the customer's phone.
However, geographical areas described by postal ZIP codes do not necessarily correspond to the geographical service areas provided by cellular communication systems. For example, the selected wireless provider may serve only a portion of the geographical area that was indicated by the customer as being the customer's “home area”, and in all other portions of the customer's “home area” another service provider or providers may be required, thereby resulting in the customer paying roaming undesirable roaming charges.
Thus, a need exists to more closely relate the communications home area of the mobile station to the end user's home ZIP code.
A need also exists to avoid roaming charges when a customer of a prepaid wireless communications system provider operates within a geographical area that was designated by the prepaid wireless communications system provider as being the customer's home area.